Producing a product from a rolled strip material

ABSTRACT

A product is produced from a rolled strip material with the steps: providing a substrate in form of a strip material from sheet steel, rolling of the substrate in form of strip material, electrolytic coating of the substrate with a first metal coating material, wherein the electrolytic coating is carried out after the rolling, applying of a second coating material as a scaling protection coating on the substrate coated with the first coating material, and hot-forming of the substrate, wherein the hot-forming is carried out after the application of the second coating material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to German Application No. DE 10 201 5202 642.6 filed on Feb. 13, 2015, which application is herebyincorporated herein by reference in its entirety.

BACKGROUND AND SUMMARY

The present disclosure relates to a method for producing a product froma rolled strip material with the steps: providing a substrate in form ofa strip material from sheet steel; rolling of the substrate in the formof a strip material, electrolytic coating of the substrate with a firstmetal coating material, wherein the electrolytic coating is carried outafter the rolling; applying a second coating material as scalingprotection coating on the substrate coated with the first coatingmaterial; and hot-forming of the substrate, wherein the hot-forming iscarried out after the application of the second coating material. Thepresent disclosure relates further to a product, produced according tothe method and made from rolled strip material.

Different methods for coating components made from steel with a zinc- orzinc-alloy layer are known, like hot-galvanizing (hot dip galvanizing)or galvanic (electrolytic) zinc-plating. Hot-galvanizing is the coatingof steel components with a massive metallic zinc coating by dipping thepre-processed steel components into a melt of liquid zinc. During theelectrolytic galvanizing the components (work pieces) are dipped into azinc electrolyte. Electrodes of zinc act, because of their more ignoblemetal compared to the work piece, as a “sacrificial anode”. The workpiece to be galvanised acts as a cathode, because of which the coatingis also designated as cathodic corrosion protection.

The document AT 412 403 B relates to a method for producing a corrosionprotected sheet steel and a sheet steel object, protected with a coatingagainst corrosion, wherein according to the process it is provided toapply in a first step at least one electrolytically produced zinc layerand at least one layer consisting of aluminium on a sheet surface, afterwhich the sheet steel is heated in a second step in a targeted mannerand is cooled. The corrosion protected sheet steel or an object formedtherefrom has a surface layer with more than 0.1 percent of mass and hasless than 5.0 percent of mass of aluminium, wherein the layer is formedfrom two intermetallic iron-zinc-aluminium phases.

From the document DE 10 2012 110 972 B3 a method for producing a productfrom flexible rolled strip material is known with the steps: providing astrip material from sheet steel; flexible rolling of the strip material,wherein a variable thickness is produced along the length of the stripmaterial; electrolytic coating with a metallic coating material, whichcontains at least 93 mass percent of zinc, wherein the electrolyticcoating is carried out after the flexible rolling; heat treating attemperatures larger than 350° C. and below a solidus line of the coatingmaterial, wherein the heat treatment is carried out after theelectrolytic coating; and working a blank from the flexible rolled stripmaterial; and cold- or hot-forming of the blank.

A thermodiffusion treatment, for example in an annealer, is carried outto enable a direct hot-forming. Otherwise, a too low iron content canlead to the effect of solder cracking during direct hot-forming.Furthermore, the iron rich intermetallic phases are brittle and tend atmechanical loading, for example by bending, to cracks, which cancontinue into the hardened material, so that a disadvantageous largebending angle results according to test specification VDA 238-100 of thematerial. A further disadvantage is that zinc has a lower vapourpressure and, thus, during thermodiffusion treatments, or a followingheating in the course of the hot-forming, leads to a zinc loss.Especially the areas of the galvannealing coating, which is close to thesurface and rich in iron, tend increasingly to an evaporation, whichleads to an only small increase of the layer thickness after thehot-forming and to a high iron content in the layer.

Disclosed herein is a method for producing a product made from flexiblerolled strip material, and a product made from flexible rolled stripmaterial, in which a heat treatment before the hot-forming can beomitted for forming an alloy.

The method according to the present disclosure for producing a productfrom rolled strip material comprises the following steps:

providing a substrate in form of a strip material from sheet steel;

rolling of the substrate as strip material;

electrolytic coating of the substrate with a first metal coatingmaterial, wherein the electrolytic coating is carried out after therolling;

applying a second coating material as a scaling protection coating onthe substrate coated with the first coating material; and

hot-forming of the substrate, wherein the hot-forming is carried outafter applying the second coating material.

According to the present disclosure, the second coating material isprovided as a compound with metallic components. In the context of thepresent disclosure, metallic components refer to components made fromelements which belong to the metals and/or, as the case may be, to thesemi-metals. The metallic components can be present as pure materials oras an alloy. The composition of the second coating material is selectedsuch that the metallic components comprise predominantly elements, whichare more ignoble than the sheet steel of the substrate to provide acathodic corrosion protection. “Predominantly” in the context of thepresent disclosure shall be understood in particular such that a portionof more than 50 percent of mass of the total metallic componentsconsists of elements which are more ignoble than the sheet steel of thesubstrate. Said mass percentage may refer to the mass in the secondcoating material before being applied to the substrate and/or to themass of the second coating after having been applied to the substrate.At least one of the elements, aluminium or manganese, belongs to theelements, which are more ignoble than the sheet steel of the substrateand which can be used.

The cathodic corrosion protection can be achieved in an advantageousmanner with the method according to the present disclosure, as theaddition of elements, which are more ignoble than the sheet steel of thesubstrate, is prevented in the first coating material and as,furthermore, no separate method step for heating between the step ofcoating and the step of hot-forming is necessary.

A further advantage of the coating produced by the method according tothe present disclosure is, that in the course of the final hot-forming areduction of the strength in the boundary area between the coating andthe substrate is achieved, so that the boundary area has an increasedductility, as compared to the hardened substrate. Advantageously, byselecting an alloy composition of the coating in a suitable manner, astep of decarburization can be omitted. In total the duration of theprocess for producing the product is shortened, which has anadvantageous effect on the manufacturing costs. A separate method stepof heating the product between the coating and the hot-forming is maynot be provided in the method according to the present disclosure.

The term substrate in the context of the present disclosure shall referin particular to at least one of a steel strip, rectangular blanksand/or form cuts, which are worked from the rolled steel strip by meansof cutting, for example mechanically or by laser cutting. The step ofworking the blanks from the steel strip is preferably carried out afterthe second coating step and before the hot-forming step. Alternatively,the step of producing the blanks, i. e. cutting can also be carried outafter the rolling and before the first coating step, so that the step ofcoating is already carried out by way of batch processing of the blanks.As strip material for the rolling, hot-strip or cold-strip can be used,wherein these terms shall be understood in the sense of common technicalterminology. Hot-strip is a rolling steel final product (steel strip),which is produced by means of rolling after previous heating. Acold-strip refers to a cold rolled steel strip (flat strip), wherein thelast thickness reduction is carried out by rolling without previousheating.

The rolling of the substrate can be carried out as flexible rolling,wherein a variable thickness is produced along a length of the stripmaterial. The disclosed method is particularly suitable for flexiblerolled strip material in that also in the thin portions of the stripmaterial a high ductility is achieved in the boundary area between thecoating and the strip material, thus leading to a reduced risk of microcracks.

Still further steps can be carried out between the above individualmethod steps. For example, after the rolling a straightening of thestrip can be provided. The working of the blanks from the strip materialcan be carried out before or after the coating. In connection with thepresent disclosure, the term working blanks from the strip materialshall cover all technical kinds of producing blanks from the stripmaterial. In particular, the term working shall include cutting orpunching the sheet blanks from the strip material, i.e., such that anedge remains on the strip, which is not further processed, as well as,that a simple cutting to length of the strip material into partialpieces is carried out, especially by means of a cutting process.

In the proposed method according to the present disclosure it isadvantageous that a formation of an alloy takes place between the steelsubstrate and the coating, with the coating comprising the firstelectrolytically deposited coating material and the second coatingmaterial as a scaling protection layer. Said formation of an alloy takesplace in the course of the heating to a temperature above Ac1, i. e.,the temperature at which the formation of austenite starts. In thecourse of a press hardening process, the formed alloy has a hardnesswhich can be at least 50 HV (Vickers Pyramid Number) below the corehardness of the hardened steel substrate. The coating has thus anincreased ductility. Furthermore, micro cracks, which might be formedduring the hot-forming on the surface, are prevented by the plasticdeformation in the more ductile coating as well as of the adjacent alloylayer, which enables a local formation of strain.

Furthermore, advantageously, in the two-layered structure of the first,electrolytically deposited coating material and the second coatingmaterial applied thereon, as a scaling protection layer, metallicparticles can be introduced into the scaling protection lacquer layer,which cannot electrolytically be deposited, like, for example, particlesof the elements aluminium and/or manganese. Because of a diffusionbarrier, for example by adding aluminium to the coating, it is achievedthat, in contrast to a pure zinc-iron-alloy, a further enrichment withiron is prevented during the austenitization, whereby a reduction of thecorrosion protection potential compared to a pure zinc coating after thehot-forming is prevented.

Furthermore, it is possible that the composition of the second coatingmaterial is selected such that the metallic components have a proportionof metallic particles, wherein the proportion of metallic particles, inrelation to the total metallic components of the second coatingmaterial, is especially at least five percent of mass and at the most 95percent of mass. The metallic particles contained in the second coatingmaterial, the scaling protection lacquer, have a cathodic corrosionprotection compared to the steel substrate. Furthermore, the coatingtends, during a heating to approximately 900° C. in the course of anaustenitization, only to a small extent to an oxidation or evaporation.It is possible that the proportion of metallic particles has especiallyone or more of the carbide forming elements titanium, niobium andvanadium. Furthermore, in addition or as an alternative, the proportionof metallic particles can comprise especially particles of one or moreof the ferrite forming elements chromium, aluminium, titanium, tantalum,molybdenum, vanadium and silicon. The metallic particles can alsocontain particles from a semi-metal, like in this case silicon, insofaras the corresponding characteristics of the semi-metal are present. Themetallic particles have preferably a grain size of at least 100nanometers and at the most ten micrometers.

According to an embodiment, zinc can be used as first coating material,wherein the amount of zinc is preferably at least 50 mass percent of thefirst coating, which includes the possibility that pure zinc can be usedin particular.

Furthermore, according to an embodiment, the hot-forming can be carriedout as an indirect process with the following partial steps: coldpre-forming of the substrate; heating at least one partial area of thecomponent, preformed from the substrate in a cold condition, to anaustenitizing temperature; hot-forming of the component to produce afinal outline.

Alternatively, the hot-forming can be carried out as a direct processwith the following partial steps: heating at least a partial area of thesubstrate to an austenitizing temperature; and hot-forming of thesubstrate to produce a final outline.

At a suitable stage of the process, blanks or form cuts are producedfrom the preferably flexible rolled strip material, which can be carriedout for example by mechanically cutting or by laser cutting. Blanks areto be understood as especially rectangular sheet boards, which areseparated from the strip material. Form cuts are to be understood assheet elements worked from the strip material, which outer profile isalready adapted to the shape of the final product. Here, the term“blank” is used uniformly for rectangular blanks as well as form cuts.

The sheet blanks are hot-formed according to a first variant of thedisclosed method. Hot-forming means forming processes, in which the workpieces are heated to a temperature in the region of hot-forming beforethe forming takes place. The heating is carried out in a suitableheating device, for example a furnace. The hot-forming is carried outaccording to the first possibility as an indirect process, whichcomprises the partial steps cold pre-forming of the blank to a preformedcomponent, following heating of at least partial areas of the coldpre-formed component to the austenitizing temperature as well asfollowing hot-forming for producing the final outline of the product.The austenitizing temperature shall refer to a temperature range, inwhich at least a partial austenitization takes place, i.e., wherein amicrostructure in the two phase region ferrite and austenite is present.Furthermore, it is also possible to only austenitize partial areas ofthe blank, to enable for example a partial hardening. The hot-formingcan also be carried out according to the second possibility as a directprocess, which is characterised in that at least partial areas of theblank are directly heated to the austenitizing temperature and then arehot-formed to the required final profile in one step. A previous (cold)pre-forming does not take place in this case. Also during the directprocess, a partial hardening can be achieved by austenitizing partialareas. For both processes it applies, that a hardening of partial areasof the component is also possible by means of differently temperedtools, or by using several tool materials, which enable differentcooling velocities. In the latter case the whole blank or the wholecomponent can be completely austenitized before the hot-forming process.

According to a further embodiment it is provided that, in the course ofhot-forming, a ductile alloy layer is produced in a boundary area of thesubstrate, said ductile alloy layer being produced from elements of thesubstrate, of the first coating material and of the second coatingmaterial, wherein the ductile alloy layer has an increased ductilitycompared to the substrate. Furthermore, in the course of thehot-forming, an outer alloy layer can be produced in a boundary areabetween the first coating material and the second coating material, saidouter alloy layer being produced from elements of the first coatingmaterial and of the second coating material. Preferably, the ductilealloy layer is produced from elements of the substrate and of the outeralloy layer.

Further disclosed is a product made especially from flexible rolledstrip material made from sheet steel with a coating of a first coatingmaterial and of a second material, produced according to the inventivemethod described herein. Thus, in relation to the product, the abovenamed advantages are achieved by a reduction of the strength achieved bymeans of the coating during the final hot-forming, in the boundary areabetween the coating and the substrate, by means of which the boundaryarea has an increased ductility compared to the hardened substrate. Theabove mentioned features relating to the preferred method steps,especially with regard to the coating, are transferrable to the product,so that concerning the features of the product and the advantagesrelating thereto it is referred to the above description.

SUMMARY OF THE DRAWINGS

Following, the present disclosure is described in more detail using apreferred embodiment with reference to the attached drawings. Theexplanations relate likewise to the method according to the presentdisclosure as to the product. In this case the explanations are onlyexemplary and do not limit the claimed invention.

FIG. 1 is a schematic flowchart of a method for producing a productaccording to an embodiment;

FIG. 2 illustrates a schematically represented layer structure of aproduct during the method of FIG. 1 before the hot-forming; and

FIG. 3 illustrates the layer structure of FIG. 2 after the hot-forming.

DETAILED DESCRIPTION

FIG. 1 shows a method according to the present disclosure for producinga product from preferably flexible rolled strip material 2. In themethod step V1 the strip material 2, which is also generally designatedas substrate 2 and is wound on a coil 3 in the starting condition, isworked in a rolling manner, i.e., possibly by flexible rolling. Forthis, the strip material 2, which has a substantially constant sheetthickness along the length before the flexible rolling, is rolled byrollers 4, 5 such, that it receives a variable sheet thickness along therolling direction. During the rolling the process is monitored andcontrolled, wherein the data determined by a sheet thickness measurement6 are used as an input signal for controlling the rollers 4, 5. Afterthe flexible rolling the strip material 2 has a variable thickness inrolling direction. The strip material 2 is wound after the flexiblerolling again to a coil 3, so that it can be transferred to the nextmethod step.

After the flexible rolling the strip material 2 is smoothed in themethod step V2, which is carried out in a strip aligning device 7. Themethod step of smoothing is optional and can also be omitted.

After the flexible rolling (V1) or smoothing (V2), respectively, thestrip material 2 is provided with a first coating material 1 in a methodstep V3. For this, the strip material 2 runs through an electrolyticstrip coating device 8. It can be seen that the strip coating is carriedout in a continuous process, i.e. the strip material 2 is wound off thecoil 3, passes through the coating device 8 and is again wound to a coil3 after the coating. This process management is advantageous, as thehandling effort for applying the first coating material onto the stripmaterial 2 is low and the process velocity is high. dip tank 9 of thestrip coating device 8, which is filled with an electrolytic liquid 10,through which the strip material 2 passes, can be seen. The guiding ofthe strip material 2 takes place by sets of rollers 11, 12.

In the present embodiment, the electrolytic coating takes place with ametallic first coating material, which contains preferably at least 50mass percent of zinc. By a high content of zinc, an especially goodcorrosion resistance is achieved. It is possible that the zinc contentis 100% (pure zinc). For example, for the coating anodes (not shown)made from zinc can be used, which emit during applying a current zincions to the electrolyte 10. The zinc ions are deposited on the stripmaterial 2, which is connected as a cathode, as zinc atoms and form azinc layer. Alternatively also inert anodes and a zinc electrolyte canbe used.

After the electrolytic coating (V3) the strip material 2 wound to a coil3 is provided with a second coating material 15 in the method step V4,wherein the second coating material 15 has a composition of metalliccomponents. The second coating material 15 is provided as a compoundwith metallic components in order to provide a cathodic corrosionprotection. The composition of the second coating material is configuredsuch that the metallic components consist mostly of elements that aremore ignoble than the material of the sheet steel of the strip material2. More particularly, the second coating material 15 can be a scalingprotection lacquer 15 with a high content of metallic components. Themetallic components can be provided in form of particles in a basematerial of the lacquer, wherein the metallic particles can comprise atleast one of titanium, niobium and vanadium particles. The metallicparticles comprised in the second coating material 15 can react with thebase steel material of the substrate 2 within a depth of up to 100micrometres, for example. Thereby, a ductile intermediate layer isformed between the electrolytic coating, i.e., first coating material,and the steel substrate.

The scaling protection lacquer 15 can be applied onto theelectrolytically deposited layer of the first coating material forexample by coil coating, spray painting, brushing and so on. In thepresent embodiment the scaling protection lacquer 15 is supplied from areservoir of an application roller 16 and so applied. If necessary, abaking of the lacquer 15 is carried out. Besides the protection againstoxidisation, a further advantage of the scaling protection layer is thatthe surface has a high quality. Furthermore, the frictional value can bepositively influenced by the scaling protection during the hot-formingas well as the heat absorption behaviour. A further advantage of thescaling protection is that the adhesion of the cathodic corrosionprotection layer arranged below is improved.

After applying the second coating material (V4), individual sheet blanks20 are worked from the strip material 2 in the next method step V5.Working, i.e., producing the sheet blanks 20 from the strip material 2can be carried out by punching or cutting. Depending on the shape of theto-be-produced sheet blanks 20, these can be punched from the stripmaterial as form cuts, wherein an edge remains on the strip material,which is not further used, or the strip material 2 can simply be cut tolength to partial pieces. A sheet blank 20 worked from the stripmaterial, which also can be designated as three-dimensional sheet blank(3D-TRB), is shown schematically. The term substrate is used for thestrip material 2 as well as for the blank 20.

After producing the blank 20 from the strip material 2, a forming of theblank 20 to the required final product can be carried out in the methodstep V5. According to a first possibility the blanks 20 can behot-formed directly or according to a second possibility can behot-formed indirectly.

In other words, the hot-forming can be carried out as a direct orindirect process. During the direct process the blanks 20 are heated tothe austenitizing temperature before the hot-forming, which for examplecan be carried out by induction heating or in a furnace. In this regard,austenitizing temperature refers to a temperature range in which atleast a partial austenitization (micro structure in the two phase regionferrite and austenite) is present. However, also only partial areas ofthe blank can be austenitized to enable a partial hardening, forexample. After the heating to the austenitizing temperature the heatedblank is formed in a shape giving tool 14 and at the same time cooledwith a high cooling velocity, wherein the component 20 receives itsfinal shape and is hardened at the same time.

During the indirect hot-forming, the blank 20 is pre-formed before theaustenitization. The pre-forming is carried out in the cold condition ofthe blank, which means without previous heating. During the pre-formingthe component receives a contour, which still does not correspond to thefinal shape, however is approximated thereto. After the pre-formingthen, as in the direct process, an austenitization and hot-forming iscarried out, whereby the component receives its final shape and ishardened.

The steel material should, insofar as a hot-forming (direct or indirect)is provided, have a proportion of carbon of at least 0.1 percent of massup to 0.35 percent of mass.

It is to be understood that the process according to the presentdisclosure can be varied. For example between the described stepsintermediate steps, which are not shown individually here, canadditionally be provided. For example, before the step of electrolyticcoating, the strip material can be provided with an intermediate layer,especially with a nickel-, aluminium- or manganese layer. Thisintermediate layer forms an additional protection of the surface andimproves the adhesiveness of the afterwards applied coating containingzinc.

Furthermore, it is to be understood that the process managementaccording to the present disclosure can be adapted in the sequence ofthe steps carried out. For example, the cutting of blanks can also becarried out at a different position, for example before theelectrolytical coating. If necessary, at the end a blasting of theproduced component can be provided.

FIGS. 2 and 3 show schematically the layer structure of the product,comprising the substrate 2, 20, i.e., in form of the strip material 2 orthe blank 20, the first electrolytic coating material 1, and the secondcoating material 15 in form of a scaling protection lacquer. In FIG. 2the layer structure is shown before the hot-forming (V6), which iscompared in the following to the layer structure after the hot-forming(V6) shown in FIG. 3. Before the hot-forming (V6) separate phases of thethree layers, the steel substrate 2, 20, the first electrolytic coatingmaterial 1 and the second coating material 15, in form of a scalingprotection lacquer, are present. The representation is not to scale. Todifferentiate the material of the layers before and after thehot-forming, markings have been drawn in FIGS. 2 and 3, wherein crossesschematically symbolize the second coating material 15, circlesschematically symbolize the electrolytic coating material 1 and a blank,i.e., no marking, schematically symbolizes the strip material 2, 20. Byaustenitization in method step V6 an alloy formation is achieved on therespective boundary faces of the layers. Metallic components of thescaling protection lacquer 15, for example aluminium, merge with theelectrolytic coating 1, for example from zinc, to an alloy 18. Thisalloy 18 forms together with the steel substrate 2, 20 a further alloy17. After the hardening, said further alloy 17 has a lower hardness thanthe hardened steel substrate 2, 20. This leads advantageously to animproved bending angle. Typical layer thicknesses before step V6 are,for the scaling protection lacquer 15 two to twenty micrometers, for theelectrolytic zinc-coating 1, two to ten micrometers. The layer thicknessafter the hardening in step V6 can amount to four to thirty micrometersfor the alloy layer 18 that comprises the electrolytic zinc coating 1and the scaling protection lacquer 15. The layer thickness for theductile alloy layer 17, that is made from the scaling protection lacquer15, the electrolytic zinc coating 1 and the steel substrate 2, 20, canamount to two to fifty micrometers.

1.-12. (canceled)
 13. A method for producing a product from a rolledstrip material, comprising: providing a substrate in form of a stripmaterial from sheet steel; rolling the substrate to produce a rolledstrip material; performing an electrolytic coating of the substrate witha first metal coating material, wherein the electrolytic coating iscarried out after the rolling; applying a second coating material as ascaling protection coating on the substrate coated with the firstcoating material; and hot-forming of the substrate, wherein thehot-forming is carried out after applying the second coating material;wherein the second coating material is a compound with metalliccomponents, wherein the composition of the second coating material isselected such that the metallic components include predominantlyelements which are more ignoble than the sheet steel of the substrate,thereby providing a cathodic corrosion protection.
 14. The method ofclaim 13, wherein the composition of the second coating material is suchthat the metallic components have a proportion of metallic particles.15. The method of claim 14, wherein the proportion of metallic particlesof the second coating material, in relation to a total of metalliccomponents of the second coating material, is at least 5 percent of atotal mass and not more than 95 percent of a total mass of the secondcoating material.
 16. The method of claim 15, wherein the composition ofthe second coating material is such that the proportion of metallicparticles has particles of one or more of the carbide forming elementstitanium, niobium and vanadium.
 17. The method of claim 15, wherein thecomposition of the second coating material is such that the proportionof metallic particles has particles of one or more of the ferriteforming elements chromium, aluminium, titanium, tantalum, molybdenum,vanadium and silicon.
 18. The method of claim 15, wherein thecomposition of the second coating material is such that the proportionof metallic particles has particles with a grain size of at least 100nanometers and not more than 10 micrometers.
 19. The method of claim 13,wherein zinc is used as the first coating material.
 20. The method ofclaim 13, wherein, during the hot-forming, a ductile alloying layer isproduced in a boundary portion of the substrate from the elements of thesubstrate of the first coating material and of the second coatingmaterial, wherein the ductile alloying layer has a higher ductility ascompared to the substrate.
 21. The method of claim 13, wherein, duringthe hot-forming, an outer alloying layer is produced in a boundaryportion between the first coating material and the second coatingmaterial from elements of the first coating material and of the secondcoating material.
 22. The method of claim 21, wherein the ductilealloying layer is produced from elements of the substrate and of theouter alloying layer.
 23. The method of claim 13, wherein rolling thesubstrate is carried out as a flexible rolling, wherein a variablethickness is produced along a length of the strip material.
 24. Aproduct from a rolled strip material made of sheet steel with a coatingfrom a first coating material and a second coating material, producedaccording to the steps of: providing a substrate in form of a stripmaterial from sheet steel; rolling the substrate to produce a rolledstrip material; performing an electrolytic coating of the substrate witha first metal coating material, wherein the electrolytic coating iscarried out after the rolling; applying a second coating material as ascaling protection coating on the substrate coated with the firstcoating material; and hot-forming of the substrate, wherein thehot-forming is carried out after applying the second coating material;wherein the second coating material is a compound with metalliccomponents, wherein the composition of the second coating material isselected such that the metallic components include predominantlyelements which are more ignoble than the sheet steel of the substrate,thereby providing a cathodic corrosion protection.